I Was Told By My Dr That I Have Ibs.

I was told by my dr that I have ibs. I have not had any "oscpoys" done. I struggle with my stomach on & off. It's ruining my life. I stopped eating dairy. My stool is typically soft or normal. I deal with constipation also. Today my stool was constipation, but it was dark brown & light brown mixed together. Should I be worried? It's stressing me out.